JP09-151909A, published by the Japan Patent Office in 1996, discloses a hydraulic cylinder in which a cylinder head is fixed to an open end of a cylinder tube by a plurality of head bolts.
The hydraulic cylinder expands and contracts when a working oil is supplied selectively through pipes to two oil chambers defined by a piston inside the cylinder tube from the outside. A pipe leading to one of the oil chambers is connected to the cylinder head via a joint. A pipe leading to the other oil chamber is connected to a base portion of the cylinder tube via a joint.
When the hydraulic cylinder reaches a maximum expansion state, the piston contacts the cylinder head, thereby preventing further expansion. In this state, the piston pushes the cylinder head, and as a result, a tensile load acts on the respective head bolts.
The bolts are screwed into screw holes that open onto an annular end surface of the cylinder tube. The working oil flowing between the pipe and the one of the oil chamber in the cylinder tube flows into the cylinder head via a port formed in a radial direction. A pipe attachment seat for fixing the joint is provided in the cylinder head on a periphery of an opening portion of the port. The head bolts are disposed to avoid the pipe attachment seat.